GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.2 GNGTS 2024 Fig. 1 – Example of different realizaCons of the rupture process The reference structure is a five-story reinforced concrete frame designed according to Italian regulaCons. The structure has a 15m wide square plan with three bays, each 5m long. Each floor is 3m high, totaling 15m. GravitaConal permanent loads include self-weight of structural elements, and an accidental load of 2 kN/m2 is applied to each floor. The roof has a snow load of 0.8 kN/m2. Seismic acCon is considered based on the Italian Building Code for a moderately hazardous site. A spectral analysis determines maximum stress values, and beams and columns are designed with low ducClity (Class B) and a behavior factor of 3.9. Design criteria ensure weak beam/ strong column capacity. Nonlinear Cme history analyses (NLTHA) are performed using Seismostruct sopware, considering both material and geometric nonlineariCes. InelasCc force-based beam elements are used for material nonlineariCes. Concrete strength class C28/35 and steel reinforcement class B450C are adopted. Rayleigh damping is applied, and the Hilber-Hughes-Taylor integraCon scheme is used. The summary outlines the structural design, seismic consideraCons, material properCes, and analysis methods employed in evaluaCng the behavior of the reinforced concrete frame under various condiCons. Scalar intensity measures such as peak ground acceleraCon (PGA), spectral acceleraCon at the first mode Sa(T1), and average spectral acceleraCon () are employed for fragility curve construcCon. Since the reference structure is 3D, the IM should account for the main vibraConal properCes in both direcCons. Therefore, here the spectral acceleraCon is evaluated for an average period calculated as the mean of the fundamental period values in each direcCon (FEMA, 2018): S a ( T 1 m ) = S a ( T 1 x + T 1 y 2 )